Steam generating unit



R. U. SHEIKH STEAM GENERATING UNIT Filed March 10, 1966 RAMSEY u. SHE/KH INVENTOR.

I PU. I F

March 19, 1968 Uitd ttes 3,373,7Zi Patented ar. 19, 1968 3,373,721 STEAM GENERATING UNIT Ramsey U. Sheikh, Westboro, Mass, assignor to Riley Stoker Corporation, Worcester, Mass, a corporation of Massachusetts Filed Mar. 10, 1966, Ser. No. 533,570 4 Claims. (Cl. 122-6) ABSTRACT OF THE DISCLOSURE This invention relates to a steam generating unit and, more particularly, to buckstay apparatus arranged to protect against excessive deflection of the outer walls due to internal gas pressure and against puifs and explosion of combustible gases in the combustion chamber, while permitting normal thermal expansion and contraction.

In the design of steam generating units, it is necessary to incorporate provisions to allow for the expansion of the periphery of the cross-section of the combustion chamber as the temperature of the unit rises and to protect against the effects of excessive deflection due to internal gas pressure. Although a certain amount of increase in the size of the combustion chamber is permissible, means must be provided to protect against the effects of an explosion in the chamber. Also it is desirable to support the wall when in its expanded condition during normal operation. This becomes a problem particularly in the case of pressurized furnaces wherein the interior pressure is greater than the exterior pressure. In the past, various methods have been proposed for performing this dual function; while many of them are adequate, they are usually expensive, since they involve intricate mechanical devices which add a great deal to the cost of the steam generating unit. These and other difliculties experienced with the prior art devices have been obviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the invention to provide a steam generating unit provided with effective means for permitting thermal expansion of the combustion chamber, while protecting against the effects of an explosion.

Another object of this invention is the provision of a steam generating unit having a buckstay arrangement which is effective in operation and which, nevertheless, is simple and inexpensive.

A further object of the present invention is the provision of a steam generating unit having a thermal expansion apparatus which is rugged in construction and which is capable of a long life of useful service with a minimum of maintenance.

It is another object of the instant invention to provide a steam generating unit in which the thermal expansion is effectively regulated by simple, inexpensive means.

It is a further object of the invention to provide a steam generating unit having buckstays and bracket devices in which the general geometric relationship of the walls of the furnace to the buckstay flanges is maintained by brackets, but in which the main means supporting the furnace walls is brought about by means other than the brackets.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

The character of the invention, however, may be best understood by reference to one of its structural forms as illustrated by the accompanying drawings in which:

FIG. 1 is a perspective view showing a steam generating unit embodying the principles of the present invention,

FIG. 2 is a sectional view of the apparatus taken on the line IIII of FIG. 1, and

FIG. 3 is a horizontal view of a steam generating unit making use of the present invention.

Referring first to FIG. 3, wherein is best shown the general features of the invention, the steam generating unit, indicated generally by the reference numeral 10, is shown as having four vertical walls 11, 12, 13, and 14 defining a combustion chamber 15. Extending parallel to the wall 11 is a buckstay 16, while similar buckstays 17, 18, and 19 extend parallel to and are spaced from the walls 12, 13, and 14, respectively. Connecting the walls to the buckstays are brackets 32. As is evident in the drawing, the ends of the buckstays 16, 17, 18, and 19 are welded together to form a rigid rectangular configuration.

Referring to FIGS. 1 and 2, which show the details of the invention, the wall 14 is shown as composed of a series of vertical water-wall tubes 21 held in spaced, parallel relationship by intermediate metal strips 22, each strip being welded to its adjacent tubes to form a monolithic wall. The channel 19 is an I-beam arranged with its web 23 extending horizontally and at a right angle to the plane of the wall 14 and its flanges 24 and 25 extending vertically. Welded to the outer surfaces of the tubes 21 between the flange 25 and the wall 14 is a channel 26 in the form of a C-channel whose web 17 lies against the tubes and whose flanges 28 and 29 extend at right angles to the general plane of the wall 14. The space between the flanges 23 and 29 is filled with insulation 31.

Welded to the upper horizontal surface of the flange 28 is a bracket 32 which is formed of heavy steel plate bent at a ri ht angle to provide a flat portion 33 which lies against the tubes 21 and a portion 34 which extends at a right angle to the portion 33 and which has a part of its bottom edge welded to the flange 28 of the channel 26. The portion 34- extends beyond the channel and is provided on the overhanging part of its lower edge with a notch 35 having a vertical edge 36 which is in the same vertical plane as the outer edges of the flanges 28 and 29 of the channel 26. The notch is at least partially formed by making parallel cuts defining a strip 37 which is bent at a right angle to the plane of the portion 34 and which has a horizontal undersurface 38 adapted to rest on the upper edge of the flange 25 of the buckstay. Welded to the other flange 29 of the channel is a bracket 39 which is exactly similar to the bracket 32. It is similarly notched to provide a vertical edge 41 lying in the plane of the outer edges of the flanges 28 and 29 of the channel and to provide a tab 42 having an upper hori zontal surface for engagement with the bottom edge of the flange 25. Overlying the wall 14 is a blanket 43 of insulation having a bottom edge resting on the upper horizontal surface of the flange 28 of the channel. A similar blanket 44 underlies the channel 26 and has an upper edge engaging the lower horizontal surface of the flange 29 of the channel.

The operation of the invention will now be readily understood in view of the above description. When the hot gases of combustion pass through the combustion chamber 15, the walls 11, 12, 13, and 14 are heated. As they are heated, being formed of metal, they expand. This means that the outer surfaces of these walls move closer to their respective buckstays 16, 17, 18, and 19. In the case of the wall 14 and the buckstay 19, as the wall moves toward the inwardly-directed vertical surface of the flange 25 of the buckstay 19, it carries with it the channel 26. Sliding takes place smoothly because of the engagement of the upper and lower edges of the flange 25 of the buckstay with the undersurface 38 of the strip 37 or with the upper horizontal surface of the tab 42, respectively. Eventually, the furance expands to its normal operating condition and, at that time, the size of the notches has been selected so that the surface of the flange 25 is engaged by the outer edges ofthe flanges 28 and 29 of the channel. At that time, the forces due to internal pressure in the chamber begin to exert themselves against the buckstays. The rigid structure, formed by welding the buckstays 16, 17, 18, and 19 together, begins to be subjected to the outwardly directed pressure forces of the furance. The buckstays are designed to be rigid and to resist further expansion of the furance due to internal gas pressure. The forces that are developed in this way are absorbed by the buckstays well within their ability to resist such force as determined by well-known engineering principles.

It can be seen that these pressure forces are directed between the wall 14 and the buckstay 19 by the rigid structure defined by the channel 26 and to a lesser extent by the brackets 32 and 39. The brackets are, therefore, not subjected to the full forces but only to a small portion thereof and they act to regulate and keep the buckstay and the channel in suitable alignment. For instance, it is important that the edges of the flanges 28 and 29 engage the flange 25 of the buckstay at equal distances above and below the web 23 since the web 23 contains the centroid of the cross-section of the beam. As is Well known, the beam presents its greatest strength resistance to bending when the resultant of the forces passes through the centroid and, when this relationship exists, is best able to resist outward expansion of the furnace without undue twisting of the buckstay; furthermore, the forces are transferred along the entire length of the buckstay, because the buckstays and the channels are coextensive.

It can be seen that with the present arrangement a simple, rugged construction has been evolved in which relatively delicate portions of the apparatus are not called upon to transmit the forces between the furance and the bucktsay but are only called upon to regulate the relationship properly in all the elements in place. By suitably guaranteeing against vertical displacement of the channel 26 relative to the centroid of the buckstay it is assured that the forces transmitted from the wall to the buckstay resist to their greatest extent. This is done with apparatus which requires no maintenance and which is inexpensive to manufacture. At the same time, the buckstays are available as rigid belts to resist explosion forces if such should occur.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent is:

1. A steam generating unit, comprising:

(a) a combustion chamber having walls defined by vertical tubes, the combustion chamber being rectangular in horizontal cross-sectional shape,

(b) a buckstay extending horizontally along each wall, the buckstay having a vertical flange from which a horizontal web extends outwardly, there being four buckstays provided at each of a plurality of horizontal levels, the ends of the four buckstays being fastened together at the corners of the chamber,

c) a channel of C-shaped cross-section welded in horizontal condition to each wall at each level with its flanges extending outwardly, and

(d) a plurality of brackets welded to the channel, each bracket being formed with a notch which embraces the edge of the flange, a flange of the buckstay extending downwardly and upwardly from the web to provide two oppositely-directed edges and wherein two brackets are provided one extending upwardly from the channel and the other extending downwardly, the notches facing one another to embrace the said edges of the flanges, the notch in each bracket being formed by bending a strip at a right angle to the vertical plane of the bracket, the strip providing a broad horizontal surface for sliding contact with the edge of the flange of the buckst-ay.

2. A steam generating unit as recited in claim 1, wherein the vertical edge of the notch closest to the wall lies in the same vertical plane as the outer edges of the flanges of the channel, so that, as the chamber expands, the inner vertical edge of each notch and the outer edge of each flange of the channel engages the facing surface of the buckstay flange.

3. A steam generating unit as recited in claim 2, wherein a blanket of flexible insulation overlies the outer surface of each wall with an edge engaging a horizontal surface of the channel and wherein the expansion of the chamber causes the edge of the blanket insulation to be compressed between the wall and the flange of the buckstay.

4. A steam generating unit as recited in claim 3, wherein the interior of the channel is filled with insulation.

References Cited UNITED STATES PATENTS 2,703,559 3/1955 Godshalk 122-6 2,987,052 6/1961 Armacost 1226 3,078,830 2/1963 Evans 1226 KENNETH W. SPRAGUE, Primary Examiner. 

